When your bottle, bladder, cup, thermos, or other drinking container is difficult to clean, don't let smells and stains build up inside. Instead, for a thorough job, use a Bottle Bright Tab. A safe and free of any harmful ingredient blend gets TO hard-to-reach areas and breaks down tough natural substances that can't be scrubbed away all the way. After, the result produces clean-tasting drinking water for your adventures.